This invention relates to magnetic tape recording and/or reproducing apparatus comprising magnetic tape and magnetic heads by which various signals can be recorded and/or reproduced.
In prior magnetic tape recording and/or reproducing apparatus , there is a one-motor system, wherein one conventional electric motor is provided and an output shaft of said motor is connected by a rubber belt with a fly-wheel attached to a tape drive capstan and which has a big inertia. Said tape drive capstan is rotated by said motor through said rubber belt and transports magnetic tape at nearly constant velocity, and at the same time, said magnetic tape is wound up by tape winding means rotated by said motor through idle wheels through a frictional slip mechanism made of materials of large frictional coefficient such as felt, which contacts with both said tape drive capstan and said tape winding means. By magnetic heads for recording and/or reproducing which contact said moving magnetic tape, various signals can be recorded and/or reproduced. For fast feed of said magnetic tape in both the forward and backward direction, another group of idle wheels are brought into contact with both said tape drive capstan and tape winding means, by which the speed of rotation of said tape drive capstan is increased and transmitted to said tape winding means to transport said magnetic tape rapidly in the required direction.
There is also a two-motor system, wherein although magnetic tape is transported by same method as described above for tape recording or reproducing, another electric motor is provided to rotate said tape winding means for fast feed of said magnetic tape in both the forward and backward direction.
In the two systems described above, because said tape drive capstan, which is most important in transporting said magnetic tape at a stable constant velocity, is driven by said rubber belt, various problems occur such as that the quality varies widely from apparatus to apparatus, and characteristics of magnetic tape transportation vary due to change of characteristics of said rubber belt because of aging, change of environment, and so on. Further, because said frictional slip mechanism which slips at a nearly constant rotational torque is used for rotating said tape winding means, problems occur as described above and the characteristics of magnetic tape transportation are caused to deteriorate.
To overcome said problems, a three-motor system or a four-motor system has been proposed, wherein said tape drive capstan and said tape winding means are each directly driven by an electric motor without any frictional slip mechanism. But, because said electric motor used in such a three- or four-motor system has a complex construction, in spite of its expensive price the characteristics of rotation of said motor is not as good as can needed for said tape drive capstan, and it is so difficult to make a practical electric motor suitable for directly driving said tape drive capstan that apparatus with such a three- or four-motor system is not widely used in general.
Further, most of the prior motors which use a commutator and a brush have only a short lifetime, and troubles due to faults of said brush often occur, and because of the use of such a brush, wow and flutter during rotation of said motor is increased.
In view of the foregoing, it is obvious that a new improved tape transporting system is required to provide a compact slim apparatus with improved characteristics for tape recording and/or reproducing without appreciable expenditure and difficulties in construction.
In U.S. Pat. No. 3,968,942, a two-motor system for tape transportation is disclosed. However, although such two-motor system is suitable for a rather compact slip apparatus with improved characteristics for tape recording and/or reproducing, the apparatus described in this patent is not very compact, and is still unsatisfactory with respect to the constancy and stability of tape transportation.